package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private SeckillVoucherServiceImpl seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;

    //秒杀优惠券lua脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    private static final String queueName = "stream.orders";

    //在类初始化好后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    public void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从redis消息队列中去拿信息
    private class VoucherOrderHandler implements Runnable {


        @Override
        public void run() {

            while (true) {
                try {
                    //1.获取队列中的订单信息 XREADGROUP GROUP  消费者组 消费者名 COUNT 1 BLOCK 2000  STREAMS 队列名 >
                    //                   XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS stream.orders >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"), // 消费者组
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)), // 获取数量
                            StreamOffset.create(queueName, ReadOffset.lastConsumed()) // 从最后一个消费的记录开始读取
                    );
                    //2.判断消息获取是否成功
                    if (list == null || list.isEmpty()){
                        //2.1获取失败，说明没有消息，继续下一次循环来获取
                        continue;
                    }

                    //3. 获取成功，可以下单
                    //3.1解析队列中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //3.2创建订单
                    handleVoucherOrder(voucherOrder);

                    //4.处理结束，确认ack，从队列中删除
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1",record.getId());
                }catch(Exception e){
                    log.error("处理订单异常：", e);
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    //1.获取pending-list中的订单信息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"), // 消费者组
                            StreamReadOptions.empty().count(1), // 获取数量
                            StreamOffset.create(queueName, ReadOffset.from("0")) // 从最后一个消费的记录开始读取
                    );
                    //2.判断消息获取是否成功
                    if (list == null || list.isEmpty()){
                        //2.1获取失败，说明没有异常消息，跳出循环
                       break;
                    }

                    //3. 获取成功，可以下单
                    //3.1解析队列中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //3.2创建订单
                    handleVoucherOrder(voucherOrder);

                    //4.处理结束，确认ack，从队列中删除
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1",record.getId());
                }catch(Exception e){
                    log.error("处理pendding订单异常：", e);
                    try {
                        Thread.sleep(20);
                    } catch (Exception e2) {
                        e2.printStackTrace();
                    }

                }
            }
        }
    }

    /*//阻塞队列
    private static final BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);
    // 用于线程池处理的任务
    // 当初始化完毕后，就会去从队列中去拿信息
    private class VoucherOrderHandler implements Runnable {
        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                }catch(Exception e){
                    log.error("处理订单异常：", e);
                }
            }
        }
    }*/

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户
        Long userId = voucherOrder.getUserId();
        // 2.创建锁对象
        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
        // 3.尝试获取锁
        boolean isLock = redisLock.tryLock();
        // 4.判断是否获得锁成功
        if (!isLock) {
            // 获取锁失败，直接返回失败或者重试
            log.error("不允许重复下单！");
            return;
        }
        try {
            //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
            proxy.createVoucherOrder(voucherOrder);
        } finally {
            // 释放锁
            redisLock.unlock();
        }
    }




    /**
     * 秒杀优惠券
     * @param voucherId
     * @return
     */
    private IVoucherOrderService proxy;
    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT, Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId));

        //2.判断结果是否有购买资格（有购买资格--> r=0 ）
        int r = result.intValue();
        if (r != 0) {
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }

        //4.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();


        return Result.ok(orderId);
    }
    /*    @Override
        public Result seckillVoucher(Long voucherId) {
            Long userId = UserHolder.getUser().getId();

            //1.执行lua脚本
            Long result = stringRedisTemplate.execute(
                    SECKILL_SCRIPT, Collections.emptyList(),
                    voucherId.toString(), userId.toString());

            //2.判断结果是否有购买资格（有购买资格--> r=0 ）
            int r = result.intValue();
            if (r != 0) {
               return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
            }


            //3.有购买资格
            //3.1 创建订单
            VoucherOrder voucherOrder = new VoucherOrder();
            long orderId = redisIdWorker.nextId("order");
            voucherOrder.setId(orderId);
            voucherOrder.setVoucherId(voucherId);
            voucherOrder.setUserId(userId);
            //TODO 保存阻塞队列
            //3.2保存到阻塞队列
            orderTasks.add(voucherOrder);

            //4.获取代理对象
            proxy = (IVoucherOrderService) AopContext.currentProxy();


            return Result.ok(orderId);
        }*/

    /**
     * 创建订单
     * @param voucherOrder
     */
     /*   @Override
    public Result seckillVoucher(Long voucherId) {
        //1. 查询秒杀券
        SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId);

        //2. 判断是否开始
        if (seckillVoucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀尚未开始");
        }

        //3. 判断是否过期
        if (seckillVoucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已结束");
        }

        //4. 判断库存是否充足
        if (seckillVoucher.getStock() < 1){
            return Result.fail("库存不足");
        }
        //获取当前用户ID
        Long userId = UserHolder.getUser().getId();


        //创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("order:"+userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        //尝试获取锁
        boolean isLock = lock.tryLock();
        if (!isLock){
            //获取锁失败，直接返回失败或者重试
            return Result.fail("不允许重复下单");
        }
     try{
         //获取代理对象(事务)
           IVoucherOrderService proxy =(IVoucherOrderService) AopContext.currentProxy();
           return proxy.createVoucherOrder(voucherId);
       }finally {
             lock.unlock();//释放锁
     }

    }*/
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //5. 一人一单
        //5.1获取当前用户ID
        Long userId = voucherOrder.getUserId();

        //5.2 判断用户是否已经购买过
        int count = query().eq("user_id", userId)
                .eq("voucher_id", voucherOrder.getVoucherId()).count();
        if (count > 0){
            log.error("用户已经购买过");
            return;
        }

        //6. 扣减库存
        /*
         * 乐观锁：使用版本号来解决超卖问题，每次执行sql语句时，查询版本号是否被改变
         * CAS方案：使用业务数据来代替版本号
         */
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherOrder.getVoucherId())// where voucher_id = ?
                .gt("stock", 0)// where stock > 0 （乐观锁CAS方案解决超卖）
                .update();
        if (!success){
            log.error("库存不足");
            return;
        }

        //7.创建订单
        save(voucherOrder);

    }
}
